Top entry ball valve and method of assembly

A top entry floating ball valve comprising:

• a valve body having a valve chamber defining a closed bottom and an opposed open sale side with inlet and outlet flow passages in communication with said valve chamber;
• a top cover plate removably mounted on said body over said open side of said valve chamber and providing an upper access opening to said valve chamber when said cover plate is removed;
• said valve body having a wall surface with an annular recess therein about said inlet flow passage and an opposed wall surface about said outlet flow passage;
• a ball closure member within said valve chamber between said opposed wall surfaces having an outer spherical surface and a central bore adapted to be aligned with said inlet and outlet flow passages;
• a downstream seat received within said recess about said outlet flow passage having an inner spherical surface contacting the outer spherical surface of said ball closure member in sealing relation;
• an upstream seat having an inner spherical surface contacting the outer spherical surface of said ball closure member and adapted to be easily inserted within and removed from said valve chamber through said upper access opening upon movement along said outer spherical surface;
• and
• a resilient spring removably mounted between said upstream seat and said opposed wall surface and frictionally slidable along said opposed wall surface for urging said ball closure member continuously into sealing contact with said downstream seat, said resilient spring being spaced from said cover plate and said closed bottom of said valve chamber.